Machine for and method of hardening cams



y 5. C. WASSON ET AL I MACHINE FOR AND METHOD OF rmnnsume cms Filed Dec. 17, 19:58 I e Sheets- Shae}: 1

INVENTORS Slowell C llassan (yard Edam ATToNY y 41-. s. c. WASSON ETAL 2,

MACHINE FOR\AND mamon OF HARDENING CAMS Filed Dec. 17, 1938 e Sheets-Sheet 2 INVENTORS Sion'ell C Wesson Beau 0 E. Garb:

ATTODRNEY May 13, 1941..

s. c. WASSON EIAL 2,242,158

MACHINE FOR AND METHOD OF HARDENING CAMS Filed Dec. 17, 1?:58

'. e Sheets-Sheet s f g ED I K m INYENTORS Sta/well C Wassaqz Be on] E Gauzn May 13, 1941.

MACHINE |I l I' m l' fi In! A I T A M 16 17 15 I s. c. wAssoN ETA| FOR AND METHOD OF HARDENING CAM;

- Filed Dec. 17, 1958" .e Sheets-Sheet 4- 0 assan Bea ATTORNEY May 13, 1941. s. c. wAssoN ETAL 2,242,153,

MACHINE FOR AND METHOD OF HARDENING CAMS Filed Deb. 17; 1938 s Sheefs-Sheet s 1! E m 150 117% 136' 135W INVENTORS glmvell c ngss 0;: BY We; #9"

\I ATTORNEY May 13, 1941. 5 w ssoN f 2,242,158

MAGHI NE FOR AND METHOD OF HARDENING CAMS Filed Dec. 17, 1938 6 Sheets-Shet 6 E 11 $1; I 74 ml E;

INVENTORS Sfon'ell C. Wesson BY Beau on! E. 6min MQ Fm ATTORNEY Patented May 13, 1941 UNITED STATES PATENT OFFICE MAICHINE FOR AND METHOD OF HABDENmG Stowell C. Wasson, Beauford E.

Gavin, and Frank R. Pollard, Indianapolis, Ind., assignors to Nationa'l Malleable and Steel Castings Company, Cleveland, Ohio, a corporation of Ohio Application December 17, 1938, Serial No. 246,402

20 Claims.

This invention relates 'to a machine for hardening selected portions of articles, such as cam shafts, crank shafts and the like, in such a man ner that the metallurgical structure of the remainder of the article does not change.

Our machine, in general, comprises a conveyor for the articles to be treated which grips the articles and carries them successively past various flame emitting burners, where they are heated to the. proper temperature. Further movement of the conveyor carries the articles to other positions wherein a stream of fluid, such as air or water, is blown on the heated portionto quench and harden the selected portion. In articles such as cam shafts, the portions to be hardened are usually in various angled positions about the longitudinal axis of the-"member. A feature of our invention is the provision of novel means for rotating the article about its longitudinal axis as it passes along the conveyor so as to bring the portions to be hardened in proper relation to one of the burners.

An object of our invention is the provision, in a flame hardening machine, of means for automatically advancing the work through the conveyor, performing the variousoperations thereupon, and finally releasing the heat treated article. In this connection, we provide novel means for gripping the ends of the articles and other I means for discharging the articles from the gripping device after the heat treatment is finished. In addition, we provide a novel mechanism for intermittently advancing the articles to position them for selected times beneath the burners.

Other objects and features of our invention will be best understood from consideration of the following description, taken in conjunction with the drawings, in which: a

Figure 1 is a view in side elevation of a machine embodying our invention.

Figure 2 is a plan view of the machine shown in Fig. 1.

Figure 3 is a partial sectional view taken generally along the line 33 of Fig. 2, illustrating certain details of the invention Figure 4 is a partial sectional view along line l4 of Fig. a.

Figure 5 is a partial vertical sectional" view, taken along the line 5-5 of Fig. 1.

Figure 6 is a sectional view through one of the chucks.

Figure 7 is an end view of the chuck shown in Fig. 6.

Figure 8 is a partial sectionalview taken genthe jaws I5, as by a key 21, is a pinion 28 engaging an erally along the line 8-8 of Fig. 3, showing one of the chucks in open position.

Figure 9 is a partial view showing a detail of a part of the conveyor.

Figure 10 is a plan view of the operating mechanism for the piston control valves.

Figure 11 is an isometric view of a part of the hollow shaft I2 is pivotally mounted on shaft II,

and at each end of shaft I2 there is'rigidly se-' cured a sprocketwheel I3, the latter and shaft I2 comprising the supporting structure for the conveyor. Secured to the inner side of each sprocket I 3 are bosses I4 (Fig. 5 each of which pivotally supports a hollow shaft I5. The bosses shown in the present application are equally spaced about sprocket I3, the desired spacing and the number required being determined by the numberof cams or other surfaces on the article which it is desired to harden. On the inner ends of each shaft I5 is mounted a chuck I6 which comprises a base member I1 secured to shaft I5, and a pair of jaws I8 each pivoted on a pin I9. The jaws are shown in the-form of bell-crank levers, one of the arms of each having a surface 20 for clamping the work-piece and another arm 2| operatively connected to a reciprocating element 22. In the present embodiment each' of the arms 2| is adapted to enter a recess in member 22 so that movement of said member in one direction tends to pivot the jaws to open position, whereas movement in the opposite direction closes the jaws. Connected to member 22 and extending through shaft I5 is a jaw-operating rod 23. The outer end of each rod 23 is formed with a head 24. A compression spring 25 bears at one and against head '24 and at the other end against a spring seat 26. Head 24 and hence operating rod 23, are thus normally held in an outward position which rotates chuck jaws I8 toward each other, so as to clamp an object therebetween. Movement of head 24 and rod 23 to the left, as viewed in Fig. 8, rotates to open position. Secured to each shaft internal gear which is fixedly mounted in a framework 39 adjacent sprocket wheel l3.

It will be understood that each chuck assembly is the same as above described and likewise that the chucks on the opposite sprocket wheels are arranged in opposite pairsso that the article can be held transversely of the machine by a pair of chucks, one on each sprocket. Moreover, one internal gear 35 is mounted adjacent each sprocket. As the sprocket wheel is rotated in the manner to be later described, the pinions mesh with the teeth ofthe internal gears and rotate the chucks, each about its own longitudinal axis.

Mounted on the rear of frame 9 on a shaft 29 are sprocket wheels 31 operatively joined with sprockets |3 by chains 38. On the same shaft as sprockets 31 and secured topivot therewith is a toothed element 39. Also on the shaft 29 is a freely rotatable member 49 having an arm 4| adapted to raise and lower pawl 42 into and out of engagement with teeth 43 on element 39. Rearwardly of sprocket 31 is a cylinder 44 provided with a piston 45' (see Fig. 14). Piston rod 46 extends outwardly of said cylinder and is joined with arm 41 of member 49 through a link 48. A pawl 49 pivoted to arm 41 is adapted to engage teeth 43 to rotate element 39 and hence sprocket 31 upon actuation thereof by the piston in cylinder 44. i

Operation of the conveyor thus far described is as follows: Upon the admission of air to the right-hand side of cylinder 44, piston 45 moves to the left, as viewed in Fig. 1 or 14, causing pawl 49, through arm 41, link 48 and piston rod 46, to rotate element 39 and hence the sprocket 31 in a counter-clockwise direction. As this rotation occurs, arm 4| of member 40 permits the first adjacent tooth 43to slip beneath pawl 42, but since arm 4| rotates with member 40, pawl 42 is permitted to drop and enter the space between the first and second adjacent teeth 43, thus forming a stop against further rotation of sprocket 31. Sprocket 31 thus moves one-sixth of a revolution, in the embodiment shown, upon each stroke of piston 45. However, since sprocket 31 is formed one-half the diameter of sprocket I3, the latter only moves one-twelfth of a revolution, thus rotating a given pair of chucks from the position illustrated at A (Fig. 1) to a position illustrated at B. The above described mechanism provides a simple and effective way of moving the articles to various positions and positively stopping them at a predetermined position in the machine. 1

The embodiment of the invention shown in the application is designed for hardening the cams on automobile cam shafts, one-of which is shown in Figs. 12 and 13 of the drawings. This cam shaft is for a six-cylinder automobile and therefore has twelve cams arranged along the longitudinal extent of the shaft and assuming various angled positions about the circumference of the shaft. As shown in Fig. 13, the cams are arranged substantially in pairs about the shaft, each pair being spaced at an angle of 60 degrees from the pair immediately adjacent thereto. In each pair the two cams are offset at a slight angle to each other due to the fact that one operates an intake valve and the other operates an exhaust valve.

Mounted above framework 9 is a burner supporting framework 60. .At the upper front end of this framework we provide tubes 6| and 32 upon which is slidably mounted the forward burner carrier 93. Upon bumei carrier 89 are mounted two pairs of burners 64, 69 and a single burner 88. As is clearly shown in Fig. 3', each burner is mounted on carrier 63 by means of a bracket 61 projecting into a boss 88 on the carrier and adjustably secured by means of a set-screw 69. The end of each bracket is formed with a hole, receiving a rod 10 extending transversely of the machine and the rod is adjustably secured in the bracket by set-screw The other end of the rod is formed with a clamp 12 for securing the burner in position. Each burner comprises a pipe 13 connected to a source of fuel such as a combustible mixture of acetylene and oxygen, and at the opposite end, pipe 13 is divided, as at 14 and 15, so as to direct a flame on each side of the part of the cam to be hardened. Pipes I4 and 15 may be provided with suitable tips on the ends thereof, so as to direct the flame in the most eflicient manner onto the cam. As shown in Fig. 2, each division 14 and I5 is formed of two pipes so that the flame from each burner is substantially the width of the cam; although, if desired, single pipes 14 and 15 may be used and provided with a multiple flame tip. By reason of the adjustable mounting of the burners on the burner carrier each burner may be positioned to direct its flame upon a cam and thus correct for the slight difference in the angular relation between the cams of each pair. Moreover, adjustments can be made to utilize the machine for cam shafts of different types. At the rear of frame 89 is a rear burner carrier slidably mounted on hollow tubes 86 and 81. Pairs of burners 98, 89 and 90 and a single burner 84 are mounted on carrier 85 in the same manner as the burners on forward carrier 83.

At the front end of the machine is a loading carriage 9| having a platform 92 with notched ends 93. At the center of platform 92 is a block 94 having a semi-circular groove 95 in the top thereof. Adjacent block 94 is a block 96 having a recess 91 shaped to fit one of the cams. As can be seen in Fig. 3, recess 91 is at an angle so as to initially position the cam shaft such that as it passes through the machine the various cams will be rotated into proper relation with the burners. When the cam shaft is placed in carriage 9| with the shaft resting in grooves 93, cam b (Fig. 4) in recess 91 and the shaft immediately adjacent the aforesaid cam in groove 95, the shaft may be pushed laterally until the lower portion of the cam b in recess 91 engages the adjacent wall of block 94 directly below groove 95. In this manner correct positioning of the cam shaft laterally of carriage 9| is assured. At one side of carriage 9| are grooved wheels 98 which rest on a rail 99 of less width than the grooves in the wheels. On

the opposite side of the carriage is a pair of wheels I09 having V-shape grooves |ll| therein. These wheels rest upon a rail I92 having a'shape corresponding to that of grooves ||l| so that the carriage is positioned laterally of the machine.

Assuming a cam shaft first correctly positioned in carriage 9| and then clamped between a pair of chucks l6, rotation of sprocket wheels |3 in a counter-clockwise direction, as viewed in Fig. 3, will cause the cam shaft to rotate in the opposite or clockwise direction. Internal gears 35 have ten times as many teeth as pinions 28, and the latter in rotating once around gears 35 make nine complete revolutions about their own axes, one revolution being lost due to the fact that the pinions are themselves rotating in a circle. As each pinion is moved one-twelfth of the cirv 5,242,158 cuniference of its internal gear at each stroke' of the piston 45, it will rotate three-fourths of a revolution about its own axis in moving from one indexed position to the next. In Figs. 12 and 13 the various pairs 'of cams have been given similar reference letters so that they can be more readily identified. In Fig. 3 there are shown the various positions taken by the first cam a of Fig. 12. It can be seen that this cam has rotated about its own axis three-fourths of a revolution in a clockwise direction between successive positions about the circumference of the conveyor. Cams (1', a being the -flrst to be heated, are indexed beneath burners 64. As the conveyor moves in the machine, cams b, b are heated by burners 65, cams c, c by burners 66 and 84, cams d, d by burners 88, cams e, e by burners 89, and camsj, f by burners 90.

The dot-dash lines of Fig. 3 show the positions of cam a as it approaches and leaves a position wherein it is midway the tips at the ends of arms 14 and 15 of the burner. It will be ob served that inapproaching this position the point of the cam rotates easily into place without interfering with the tips of the burner. Likewise, in leaving the position it rotatesin a clockwise direction so as to miss hitting the tip on arm I4. As will be later described, the indexing mechanism for shifting the cam from one position to another may be adjusted so as to permit the cam to remain beneath its burner for a sufflcient time to raise the surfaces to 'be hardened to the desired temperature. After being heated the cam is moved to the next indexed position. At this location, that is, one-twelfth of a revolution in the present machine from the heating position, we have provided means for quenching the heated surfaces so as to obtain the desired hardened structure. A pipe I09 is secured to arm I4 of burner 64 and is bent at one end, as

at II 0, so as to direct a stream of fluid, such as air or water, against the heated surfaces of the cam. The' other end of pipe I08 is connected to a source of fluid under pressure. After a given pair of cams is cooled, the cam' shaft continues its movement through the machine and in each position one pair of cams is being heated and another pair cooled, in the manner described above, until all of the cams have progressed through the hardening cycle. In the last position of this cycle, as shown at C (Fig. 1), no heating takes place, inasmuch as the cams have already passed through six heating positions; thus there only remains the step of quenching the last pair of cams to be heated. When a cam shaft reaches position D (Fig. 3) the chuck jaws are automatically opened to release the shaft.

We provide means for opening the chuck jaws to insert the shafts in the following manner: Cylinders III, one on each side of the machine, have pistons II2, the piston rods of which extend towards the center of the machine and may be formed with flat plates I I3 on the ends thereof. These plates lie adjacent opposite pairs of chucks when the latter are in position for loading. Pistons II2 are pneumatically actuated and the air to the cylinders is controlled by a manually operated valve II4. Upon operation of the valve, air is admitted to the outer ends of cylinders III and the pistons are forced towards each other, causing plates II3 to force the chuck operating rods 23 inwardly to open the chuck jaws in the manner previously described. It will be observed from Fig. 2 that in the loading position the chuck jaws are vertical, that is, one

above the other, so that when they are opened, carrier OI with its cam shaftin position for loading may be rolled so asto position the shaft between the open laws of the chucks. Upon release of valve II4, pistons II2 are moved in the opposite direction and springs 25 expand and close the chuck jaws on the cam shaft.

Similar-l means is provided for releasing the cam shafts from the chucks after the hardening operation. Cylinders IIS are4nounted on framework 9 on either side of the machine and are located opposite the ends of a cam shaft when the latter is in its lowermost position in the piston I 2| and piston rod I connected to burner carrier machine. Pistons I IS in said cylinders have piston rods extending, towards each. other and may be provided with flaring centering cups III adapted to engage the heads 24 of a pair of oppositely disposed chuck operating rods. When pistons IIG are forced towards each other by the entry of air in the outer ends of cylinders I IS, a pair of the chucks are opened and .the' cam shaft held therebyis discharged from the machine. The cups III may be flared, as shown in Figs. 5 and 8, so that, upon engagement therewith with heads 24 the flaring walls H8 serve to correctly position the sprocket wheels I3 in such a manner that the pair of chucks tobe next loaded will be in proper relation to the loading carriage. The flaring walls III on cap III may not be necessary in all cases, inasmuch as the pawls 42 and 49 ofthe indexing mechanism should of themselves locate the chucks in the piroper relation to the burners and loading carr age.

In some instances it may be necessary to move the burners closer to the cams than is shown,

interference we provide means for shifting the burner carrier laterally of the machine so as to position the burners to one side or the .other of the cams. As has been previously stated, burner carriers Stand 85 are slidably mounted on tubes 6| and 62, and 86 and 81, respectively. At one sideof the machine is a cylinder I28 having 9. I22, the latter being 85 through a bracket I23. The piston is pneumatically actuated. to shift burner carrier 85 laterally of the machine, and burners 84, 88, 89 and 90 are moved to positions between certain of the cams. Cylinder I24, on the opposite 'der I20, has a. piston I25 and piston rod I26 connected to a bracket I21 on carrier 63 to move the latter, and hence burners 64, 65 and 66, laterally of the machine to positions between certain others-of the cams. Stop collars I28 are provided to limit movememt of the burner carriers. The burner carriers are shown as being shiftable in opposite directions for the reason that the cam shaft illustrated herein has bearing portions 9, h and i and gear 1 which necessitates movement of adjacent burners away from said portions to clear the associated cams. For instance, cam a (Fig. 12) is adjacent bearing i so the burner 64 that heats cam a moves from the full lineposition to the position shown in dot-dash lines.

side of the machine from cylin- -valve has a bell-crank lever 4 mechanism for operating the valves controlling the indexing, unloading and burner shifting cylinders and the air or water quench. The mechanism is mounted on the main frame of the machine beneath the loading station, as shown in Fig. 1. (To avoid confusion the timing mechanism is not shown in Fig. 2.) Secured to shaft I30 are cams I3I, I32, I33 and I34 for operating respectively air quench valve I35, indexing valve I36, unloading valve I31 and burner shifter valve I38. Shaft I30 is rotated, through a speed reducer, by a motor I39 and belt I40. Each I4I pivotally mounted on the top thereof provided with a roller I42 adapted to be engaged by the respective cams for rocking each lever about its pivot. Valves I36, I31 and I38 are four-way valves of standard make and each has a pair of plungers I43 (Fig. 14) adapted to slide on members I for controlling the direction of air flow into double acting cylinders 44, H and I20. Each plunger I43 is formed with an internal groove so as to provide an air chamber I45 between the plunger and member I44. When a plunger is in lowermost position, the air chamber I45 spans ports I46 and M1 in member I44 permitting air to pass from air supply line I48 through the valve to one end of a cylinder. When a plunger is in its upper position, the lower port I46 is open to the atmosphere and permits air to be exhausted from a cylinder.

Each of bell-crank levers I on valves I36, I31 and I38 has a pair of arms I50 connected by rods I5I to the plungers of the valve, thus when one plunger I43 in a given valve is up the other plunger is down. A spring I52 between one of the plungers and top wall I53 of each valve normally maintains the plungers in such position as to hold the pistons in the respective cylinders in retracted position; Valve II4, which controls the loading cylinder, is the same as the valves just described except it is manually operated. Valve I35 has only one plunger since its purpose is to control the air or water supply used for cooling the heated cams on the cam shaft being treated. Pipe I54, leading from valve I35, is joined with pipes I09 which direct the cooling fluid (air in the present instance) against the heated surfaces of the cams.

The operating of the timing mechanism is as follows: Assuming the machine loaded with cam shafts between each pair of chucks in the first nine positions of the conveyor starting with the loading station, cam I34 of the timing device operates valve I38 admitting air into the outer ends of cylinders I and I24 to shift the burner carriers and holds the latter in shifted position until indexing cam I32 operates valve'I3Ii to actuate piston 45 and move the conveyor to its next position. Cam I34 then releases valve I38 and air is admitted to the inner ends of cylinders I20 and I24 shifting the burner carriers to their normal positions, whereupon the cams of the articles being treated are heated by flames from the various burners. Immediately after the conveyor has been moved to a new position, cam I33 of the timing device operates valve I31 actuating pistons H6 and opening the pair of chucks at the unloading station. It will be observed that cam I33 holds valve I31 in chuck opening position and maintains cups III in engagement with heads 24 substantially all the time the heating operation is taking place, thus effectively precluding the conveyor from shifting during this portion of the cycle. Shortly after the conveyor has moved to a new position (in the order of two to ,five seconds), cam I3! opens valve I causing an air blast to pass through pipes I09 which cools the surfaces of the cams heated in the previous position of the conveyor. The time interval of from approximately two to five seconds is to permit the heat to'penetrate into the cam and obtain a substantial thickness of hard metal.

We prefer to adjust the speed of the timing shaft I30 so that the period the cams are heated is about fifteen seconds. However, since the speed of the timing mechanism must be correlated with the temperature of the burner flame the two may be varied at will so as to obtain the desired hardness of cam surface. Moreover, cam I3I may be shifted on shaft I30 to turn on the cooling air sooner or later than herein indicated so as to change the characteristics of the metal being treated.

The terms and expressions which we have employed are used as terms of description and not of limitation, and we have no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof, but recognize that various modifications are possible within the scope of the invention claimed.

Whatwe claim is:

1. In a method of tempering metallic articles consisting of, causing a succession of said articles to travelalong a predetermined path with a regularly intermittent motion with periods of rest between the steps of said motion during which periods said articles are held stationary, rotating said articles between points of rest in said intermittent motion to move selected portions thereof to predetermined positions, successively exposing said selected portions of each article to the heating effect of a high temperature flame during said periods of rest and when in said predetermined positions and quenching said articles.

2. In a method of tempering metallic articles consisting of causing a succession of said articles to travel along a predetermined path with a regularly intermittent motion with periods of rest between the steps of said motion during which periods said articles are held stationary, rotating said articles between points of rest in said intermittent motion to move selected portions thereof to predetermined positions, successively exposing said selected portions of said articles to the heating effect of a high temperature flame at one position of rest and when in said predetermined positions and thereafter quenching at the next position of rest of said articles.

3. In a'method of tempering metallic articles consisting of causing a succession of said articles to travel along a predetermined path with a regularly intermittent motion with periods of rest between the steps of said motion during which periods said articles are held stationary, rotating said articles between points of rest in said intermittent motion to move selected portions thereof to predetermined positions, successively exposing said selected portions of said articles to the heating effect of a high temperature flame at one position of rest and when in said prdetermined positions, thereafter quenching at the next position of rest of said articles, and releasing each article after all of said selected portions thereof have been heated and quenched.

4. In a flame hardening machine, means for intermittently moving articles to be hardened through the machine and for holding said articles stationary during periods ,of rest in said movement, means for rotating said articles each about its own axis, only during said movement, means directing a high temperature flame on selected portions only of said articles during periods of rest and means for quenching the heated selected portionsof said articles.

5. In a flame hardening machine, an intermittently movable conveyor, said conveyor being adapted to receive articles to be hardened, means for rotating said articles only during said intermittent movement of the conveyor, means directing a high temperature flame on selected portions only of said articles for a predetermined interval during a, period of rest in said intermittent movement, and means for quenching the heated selected portions of said articles after a M predetermined time from the end of said interval.

6. In a machine for hardening cam shafts having a plurality of cams disposed in angular relation about the shaft, comprising a plurality of flame emitting burners, means for moving the cam shafts into positions to be heated by said burners, means for arresting movement of the cam shafts for a predetermined interval in each of said positions, and means for rotating said cam shafts between successive positions to bring various ones-of the cams into heating relation to the burners.

7. In a machine for hardening selected portions only of articles wherein the selected portions are disposed in various angled positions about the article, comprising a conveyor for the articles, means associated with said conveyor for rotating the articles each about its own axis only while traveling'with said conveyor to bring said portions to predetermined stationary positions in said machine, a plurality of flame emitting burners adjacent said conveyor-placed in heating relation to said portions, and means for arresting movement of said conveyor forpredetermined intervals when said selected portions are in heating relation to said burners.

8. In a machine for hardening selected portions only of articles wherein the selected portions' are disposed in various angled positions about the article, comprising a conveyor for the articles, means associated with said conveyor for rotating the articles each about its own axis only while traveling with said conveyor to bring said portions to predetermined stationary positions in said machine, a plurality of flame emitting burners adjacent said conveyor placed in heating relation to said portions, means for arresting movement of said conveyor for predetermined intervals when said selected portions are in heating relation to said burners, and means for quenching said selected portions after being heated.

9. In a machine for harde'ningcams on cam shafts, a conveyor for intermittently moving the shafts through the machine, a plurality of burners positioned in heating relation to the'cams on said shafts at points of rest in said intermittent movement, means for rotating the shafts only between successive points-of rest to bring various cams thereon into fixed heating relation to the burners, and means for quenching the heated portions of the shafts.

10. In a machine for hardening protruding cams on cam shafts, comprising an intermittently moving conveyor for said shafts, a plurality of burners spaced about said conveyor, each burner being positioned so as to be in heating relation to one of the cams on a shaft during a period of rest in said intermittent movement, means forrotating said shafts each about its own axis only while moving from one position of rest to the next succeeding position of rest, and means for shifting said burners out of heating relation to the cams during movement of the conveyor between successive positions of rest.

11. In a machine for hardening protruding cams on cam shafts, comprising an intermittently moving conveyor for said shafts, a plurality of burners spaced about said conveyor, each burner being positioned so as to be in heating relation to one of the cams on a shaft during a period of .rest in said intermittent movement, means for rotating said shafts each about its own axis only while moving from one position of rest to the next succeeding position of rest, means for shifting said burners out of heating relation to the cams during movement of the conveyor between successive positions of rest, and means for quenching saidheated cams.

12. In a machine for hardening protruding 'cams on cam shafts, comprising an intermittently moving conveyor for said shafts, a plurality of burners spaced about said conveyor, each burner being positioned so as to be in heating relation to one of the cams on a shaft during a period of rest in said intermittent movement, means for rotating said shafts each about its own axis only while moving from one position of 'rest to the next succeeding position of rest,

means for shifting said burners out of heating relation to the cams during movement of the conveyor between successive positions of rest, and means for quenching each cam in the position of rest next succeeding that in which it was heated.

13. In a flame hardening machine comprising a conveyor, means for intermittently moving said conveyor, pivotally mounted clamping means on said conveyor for holding the articles to be hardened, an internal gear adjacent said conveyor and a pinion on said clamping means engaging said gear for rotating said means onlyuponmovement of said conveyor, and a plurality of flame emitting burners positioned about said conveyor so as to be in heating relation to the articles to be hardened during periods of rest in said intermittent movement.

14. In a machine for hardening cams on cam shafts, an intermittently moving conveyor adapted to receive the cam shafts, means for rotating said shafts each about its own axis only during movement of said conveyor, a plurality of bumers positioned so as to be in heating relation to the cams on the shafts during periods of rest in said intermittent movement, a platform for loading the shafts in the machine, and means on said platform for initially positioning the cam shafts tent movement, means for quenching the heated 4 portions of said articles, and timing means for causing operationof said conveyor and quenching means.

16. In a machine for hardening protruding cams on cam shafts, comprising an intermittently moving conveyor for said shafts, a plurality of burners spaced about said conveyor, each burner being positioned so as to be in heating relation to one of the cams on a shaft during a period of rest in said intermittent movement, means for rotating said shafts each about its own axis only while moving from one position of rest to the next succeeding position of rest, means for shifting said burners out of heating relation to the cams during movement of the conveyor between successive positions of rest, and timing means for causing operation of said conveyor and shifting means.

17. In a flame hardening machine, a plurality of flame emitting burners spaced about said machine, a conveyor successively moving articles into and out of the zones of said flames, means for rotating said articles each about its own axis during said movement and for stopping rotation of said articles during periods of rest in said movement so as to bring selected portions of said articles in the zones of said flames, and means for quenching said selected portions after passing out of said zones.

18. In a flame hardening machine, a conveyor comprising a pair of oppositely disposed rotating elements, gripping means on said elements for holding the articles to be hardened, means for intermittently moving said conveyor, a burner, means for rotating said gripping means during said movement to bring said articles to predetermined stationary positions inlsaid machine and for stopping rotation of said article when in said stationary positions, said burner being adapted to direct a high temperature flame on selected surfaces of said articles when the latter are in said stationary positions.

19. In a flame hardening machine, a conveyor comprising a pair of oppositely disposed rotating elements, gripping means on said elements for holding the articles to be hardened, means for intermittently moving said conveyor to bring said articles to predetermined stationary positions in said machine, a burner, means for rotating said gripping means during said intermittent movement and for stopping said rotation when the articles are in said predetermined stationary positions so as to position selected surfaces of said articles in heating relation \to said burner, said burner being adapted to direct a high temperature flame on the selected surfaces of the articles to be hardened during periods of rest in said intermittent movement, and means for quenching said selected surfaces after a predetermined interval from said heating period.

20. In a flame hardening machine, a conveyor comprising a pair of oppositely disposed rotating elements, gripping means on said elements for holding the articles to be hardened, means for intermittently moving said conveyor to bring said articles to predetermined stationary positions in said machine, a burner, means for rotating said gripping means during said intermittent move- -ment and for stopping said rotation when the articles are in said predetermined stationary positions so as to position selected surfaces of said articles in heating relation to said burner, said burner being adapted to direct a high temperature flame on the selected surfaces of the articles to be hardened during periods of rest in said intermittent movement, means for quenching said selected surfaces after a predetermined interval from said heating period, and means for releasing said articles from said gripping means after being quenched. 

